The present invention relates to a system for controlling the ignition timing of an internal combustion engine such as an automotive engine.
A learning control system for correcting the ignition timing has been proposed. The control system is adapted to advance the ignition timing so as to produce a maximum torque as long as the level of the engine knock does not exceed a tolerable level. The ignition timing stored in a RAM is corrected by a small correcting quantity (quantity of correction) and converged to a desired value little by little. The correcting quantity for the ignition timing at every updating operation is gradually reduced as the leaving number increases, that is as the ignition timing approaches the desired value.
On the other hand, when engine operating conditions greatly change, the ignition timing deviates from a desired ignition timing. In a conventional ignition timing learning control system, a single program is provided for correcting the ignition timing in acceleration and steady state. Accordingly, it takes a long time to correct the timing.